Methods and agents for cleaning and disinfecting fragile medical appliances

ABSTRACT

The invention relates to the use of agents, which contain at least one disinfection system based on selected organic peracids and combinations of peracids, in automatically functioning systems, in which fragile medical appliances, in particular, endoscopes, are cleaned and disinfected. According to the invention, the appliances are brought into contact with an aqueous disinfection agent solution after they have been treated and/or at the same time they are being treated with an aqueous cleaning solution. The invention also relates to cleaning and disinfection agents and methods which are all suited for carrying out this purpose.

The present invention relates to the use of compositions containing atleast one disinfecting system based on organic per-acids inautomatically operating equipment in which sensitive medical apparatus,in particular endoscopes, are cleaned and disinfected, the apparatusbeing brought into contact with an aqueous disinfectant solution afterand/or simultaneously with the treatment with an aqueous cleaningsolution. The invention also relates to cleaning compositions anddisinfectants and processes suitable for the aforementioned purpose.

Endoscopes, for example flexible glass fiber endoscopes, are used inmedical diagnosis and therapy and in surgical operations. In particular,glass fiber endoscopes are extremely complicated precision instrumentswhich possess moving parts and are produced from many materials. Thecleaning and disinfection thereof is highly problematic for a number ofreasons. Thus, not only the external surfaces of the instrument but alsothe ducts with narrow lumens in the interior have to be cleaned anddisinfected in each case. The apparatus are normally first cleaned andthen disinfected by mechanical treatment processes. The thermaldisinfection preferred for medical apparatus and instruments cannot becarried out here because endoscopes are produced in part fromheat-sensitive materials. With chemothermal treatment, it should beremembered that, although glass fiber endoscopes can be fully immersedin cleaning and disinfecting baths, they withstand at most temperaturesto 70° C. without being damaged. It should also be remembered that anumber of existing metal parts are susceptible to corrosion, and theelements connecting the individual parts of the apparatus to one anothercan be attacked by the agents. Furthermore, parts consisting ofrubber-like materials may swell and stick. Finally, it should bepossible to carry out the cleaning and disinfection of endoscopes in ashort period of time so that the instruments are available again asquickly as possible for treating patients.

Mechanical treatment processes are preferred as they allow astandardized procedure which can be checked, if necessary.

A two-stage cleaning process is known from European Patent ApplicationEP-A 0 268 227, whereby the surfaces of the apparatus to be treated, insuccession, (a) are brought into contact with a cleaning solution whichis heated to 55 to 65° C., is kept at this temperature for 1 to 15minutes and is subsequently removed and which contains at least onelow-sudsing nonionic surfactant, at least one proteolytic enzyme, atleast one complexing agent and optionally further conventional cleaningcomposition constituents and has a pH of 6 to 8 and (b) are brought intocontact with a disinfecting solution which is heated to 55 to 65° C., iskept at this temperature for 1 to 15 minutes and is subsequently removedand which contains at least one aldehyde from the group consisting offormaldehyde and aliphatic dialdehydes containing 2 to 8 carbon atomsand at least one complexing agent and has a pH in the range of 6 to 8.The endoscope is subsequently rinsed at least twice with water having apH between 6 and 8, the water being heated to 55 to 65° C. in the lastrinse cycle, and is subsequently dried with sterilized hot air at 55 to65° C.

European Patent Application EP-A 0 342 499 describes a single-stageprocess for cleaning and disinfecting endoscopes, wherein the endoscopesare brought into contact with a cleaning disinfectant solution whichcontains at least one low-suds nonionic surfactant, at least oneproteolytic enzyme, at least one complexing agent and at least onealdehyde from the group consisting of formaldehyde and aliphaticdialdehydes containing 2 to 8 carbon atoms and has a pH between 6 and 8,the solution being heated to 55 to 65° C., being kept at thistemperature for 1 to 15 minutes and subsequently being removed. Thesurfaces to be treated are subsequently rinsed twice with water, thewater being heated to 55 to 65° C. at least in the last rinsing cycleand are then dried with sterilized hot air at 40 to 60° C.

It is known from European Patent Application EP-A 0 156 275 to use, asantimicrobial substances, amine compounds obtained by reaction ofcompounds of formula R¹NHCH₂CH₂CH₂NH₂, wherein R¹ represents a linearalkyl radical containing 12 to 14 carbon atoms, with compounds offormula R²OCOCH₂CH₂CHNH₂COOH, in which R² represents an alkyl radicalcontaining 1 to 4 carbon atoms or a hydrogen atom, in a molar ratio of1:1 to 1:2 at 60 to 175° C. These reaction products have also been knownas glucoprotamine.

German Patent Application DE-A-40 07 758 describes an aqueoussurfactant-containing cleaning composition and disinfectant concentratewhich contains, as antimicrobial active ingredients, the amine compoundsmentioned in European Patent Application EP-A 0 156 275 in combinationwith selected quaternary ammonium compounds. A process for the spraycleaning and disinfecting of objects from medical appliances inautomatically operated equipment is also described, which comprises thesteps a) spraying of an aqueous disinfecting cleaning compositionsolution at elevated temperature, which has been produced by dilution ofthe described cleaning composition concentrate and, optionally, b)spraying of an aqueous, optionally surfactant-containing rinsingsolution and optionally c) drying, preferably by means of hot air.

EP-A-343 605 describes a liquid aldehyde-free tuberculoidal disinfectantwhich contains N,N-bis-(3-aminopropyl)-laurylamine as active component.

European Patent Application EP-A 620 013 describes a disinfectant forcollective toilet systems and similar arrangements which is insertedmanually. It contains salts of amines of formula RN[(CH₂)_(n)—NH₂][(CH₂)_(m)—NH₂] or RNH[(CH₂)_(p)—NH₂], in which R represents astraight-chain or branched alkyl or alkenyl radical containing 6 to 22carbon atoms, n and m have a value of 4 to 12 and p has a value of 2 to12. The compositions are used at low temperatures up to 50° C. owing tothe corrosiveness in relation to metals such as steel and plasticsmaterials.

European Patent Application EP-A-0 551 975 discloses a disinfectantconcentrate and a disinfectant based on amine and alcohol and its use,the alcohol component comprising at least one aromatic alcohol and theamine component at least one secondary and/or tertiary hydroxygroup-free alkyl amine. The ready-to-use solution has a pH between 7 and12. The disinfectant is used, in particular, as a bactericide, inparticular as a mycobactericide, fungicide or virucide. European PatentApplication EP-A-0 612 170 also relates to an amine- andalcohol-containing disinfectant, wherein the alcohol component comprisesat least one glycol ether which is water-miscible to a limited extentand the amine component comprises at least one secondary and/or tertiaryhydroxy group-free alkyl amine.

Comparison experiments on fully automated cold chemical andthermochemical endoscope disinfection under practical operatingconditions have shown that neither cold chemical nor thermochemicalprocesses allowed completely satisfactory cleaning and disinfection atthat time (cf Hyg. Med. 1994, 19, 75 to 93).

The disinfectants and processes described in the foregoing documentshave a number of drawbacks. For example, disinfectants based on aminehave a tendency to attack metal and plastics materials and to destroythem at temperatures higher than 50° C., so they were expected to beunsuitable for use in mechanical treatment processes for sensitivemedical apparatus, for example endoscopes (cf. EP-A-0 620 013). Attemptshave also been made to replace the aldehydes used with other compounds,as users complain that there is a risk of exceeding MAC values and thatpersonnel involved with the cleaning apparatus may be injured by thealdehydes. Furthermore, aldehydes lead to the fixing ofprotein-containing soil if the soil has not been removed completely by apreliminary cleaning stage.

It is known that quaternary ammonium compounds have a good disinfectingaction but are attracted to surfaces and may cause adhesion.

It is known that peroxides have a broad range of antimicrobial activity.

For example, it has been proposed in German Offenlegungsschriften 26 55599 and 28 15 400 that the aqueous preparations required fordisinfection are produced just prior to use, from relatively stablepreliminary stages, namely from sodium perborate and acid anhydrides.According to German Offenlegungsschrift 27 01 133, the aqueouspreparations are obtained from hydrogen peroxide eliminators andaromatic acyloxycarboxylic acids. However, only a few of these compoundsyield disinfecting solutions with sufficiently broad activity, and theseacylation agents mixed with the necessary inorganic peroxides can onlybe stored for a limited period owing to decomposition reactions. Thereis a commercially available product known as Sekusept powder which, whendissolved in water, produces a disinfecting preparation by reaction ofsodium perborate with tetraacetyl ethylenediamine (TAED). This productwhich is based on an N-acyl compound has a broad range of activity andis stable in storage. Although this has enabled a high standard to beachieved in the disinfection of medical instruments, further attemptshave been made to improve peroxidic systems in order to overcomeremaining deficiencies and drawbacks in use. It has been proposed, forexample in DE-OS 36 15 787, that the magnesium salt of monoperoxyphthalic acid be used instead of inorganic hydrogen peroxide eliminatorsin the production of these preparations. However, the use of thisorganic peroxide involves much higher production costs than the use ofinexpensive inorganic peroxides which are stable in storage.

EP 357 238 relates to antimicrobial compositions which contain copperand brass corrosion inhibitors, a buffer substance, an anticorrosionagent which inhibits the corrosion of various metals and a wetting agentin addition to a strong oxidizing agent selected from peracetic acid andlithium hypochlorite. In the description, the patent deals in moredetail with the use of these agents for the disinfection by immersionof, for example, sensitive medical apparatus such as endoscopes and thelike. The complex composition of the peracetic acid formulationsprotected in this document is probably due to the fact that the risk ofcorrosion during disinfection by immersion is high owing to thegenerally very long contact times.

This complexity of the per-acid formulations can be avoided by carryingout processes which allow thorough cleaning and disinfection to beachieved within a comparatively short period of time. For example, EP945 140 describes a machine and a process for the washing anddisinfection/sterilization of endoscopes in which dosing agents for thedosing of oxide-based disinfecting/sterilizing solutions are used.Disinfection is therefore achieved within a short period of time.Additions of corrosion inhibitors are unnecessary. Furthermore, theautomatic cleaning, washing and disinfecting process is assisted by anadditional mechanical effect. This is achieved in that the washing anddisinfecting solution is kept in motion, at least in part, in theautomatically controlled process and an additional mechanical effect iscreated by the rinsing and/or spraying operations.

However, the use of peracetic acid in the immersion process or use ofoxide-based disinfecting/sterilizing solutions in the automatic cleaningand disinfecting of endoscopes known from the state of the art is alsoaccompanied by drawbacks. Peracetic acid itself has an unpleasant odorand is particularly problematic if it is to be used by personnel withinadequate chemical training. Furthermore, peracetic acid hasdeficiencies over the entire range of germs, in particular in the caseof fungi and yeasts. Other oxide-based disinfecting solutions are eitheraccompanied by similar drawbacks with respect to the odor or similarlyhave inadequate antimicrobial activity which is required, in particular,in relation to Mycobacterium terrae. In addition, the per-acids normallyused for disinfection purposes do not have a cleaning activity ifresidual soil has not been completely removed by a preliminary cleaningstage.

It was accordingly the object of the present invention to seekcompositions for use in automatically operating equipment in whichsensitive apparatus, in particular endoscopes, are cleaned anddisinfected, which compositions may be used in a low concentration andwith minimal odor owing to their excellent effectiveness. A furtherobject of the present invention is to achieve an additional cleaningeffect with the disinfecting solution based on organic per-acids so thatit is additionally assured that the medical apparatus are free fromresidues if cleaning in the first stage of the automatic cleaning anddisinfecting process is incomplete.

The present invention accordingly relates to the use of compositionscontaining at least one disinfecting system based on organic per-acidscomprising, as per-acids or salts of per-acids,

a) compounds of general formula I

R²—O₂C—(CH₂)_(n)—CO₃H  (I)

wherein R² is hydrogen or an alkyl group containing 1 to 4 carbon atomsand x is a number from 1 to 4 and/orb) compounds from the group consisting of phthalimido percarboxylicacids (II), wherein the percarboxylic acid content is 1 to 18 carbonatoms optionally in combination with other per-acids or containing asper-acids or salts of per-acids,c) compounds of general formula I

R—O₂C—(CH₂)_(x)—CO₃H  (I)

wherein R is hydrogen or an alkyl group containing 1 to 4 carbon atomsand x is a number from 1 to 4 and/orcompounds from the group consisting of phthalimido percarboxylic acids(II), wherein the percarboxylic acid content is 1 to 18 carbon atoms,and/orcompounds of general formula III

R—CO₃H (III)

wherein R represents an alkyl or alkenyl group containing 1 to 18 carbonatoms, in combination withc1) at least one fatty acid and/orc2) at least one hydrotrope and/orc3) at least one surfactant component and/orc4) at least one complexing componentin aqueous disinfectant solutions for automatically operating equipmentin which sensitive medical apparatus, in particular endoscopes, arecleaned and disinfected, wherein the apparatus are brought into contactwith this aqueous disinfectant solution after and/or simultaneously withthe treatment with an aqueous cleaning solution.

It is preferred if the ingredients combine to form a synergisticcombination in the aqueous disinfecting solution.

It is also preferred if the contact time between the aqueousdisinfectant solutions and the sensitive medical apparatus is between 1and 15 minutes.

The use according to the invention is preferably at a temperaturebetween 5 and 55° C., particularly preferably between 15 and 45° C.

It is also preferable if the pH is between 5 and 9, particularlypreferably 6.5 to 8, during the use according to the invention.

In a preferred practical example of the present invention, for producingthe aqueous disinfectant solution,

a) hydrogen peroxide or peroxidic compounds which form hydrogen peroxidein water are reacted in an aqueous acidic medium with carboxylic acidsor carboxylic acid derivatives which are known as starting products forper-acid compounds of formulae I, II, III, and optionally furthercomponents and subsequently

b) the pH of the preparation obtained in step a) or of the dilutepreparation is adjusted to a pH between 5 and 9, particularly preferablybetween 6.5 and 8, the use of a buffer solution intended for pHadjustment being most particularly preferred.

It is also preferred if, for producing the aqueous disinfectantsolution,

a) hydrogen peroxide or peroxidic compounds which form hydrogen peroxidein water are reacted in an aqueous alkaline medium with N-carboxylicacid amides which are known as starting products for per-acid compoundsof formulae I, II, III and optionally further components andsubsequently

b) the pH of the preparation obtained in step a) or of the dilutepreparation is adjusted to a pH of between 5 and 9, particularlypreferably between 6.5 and 8, the use of a buffer solution intended forpH adjustment being most particularly preferred.

N-acylcaprolactam and TAED are mentioned as N-carboxylic acid amides.

It is preferable if the apparatus are rinsed with water and subsequentlydried in a manner known per se after separation of the aqueousdisinfectant solution.

Preferably, the compositions to be used according to the invention areoptionally brought into contact with the medical apparatus to be treatedby spraying, rinsing, immersion and/or other procedures after anintermediate dilution or mixing stage.

Preferred practical examples of the compositions to be used according tothe invention contain

a) per-acids in which R² is hydrogen or a methyl group as per-acids ofgeneral formula I, and/or

b) phthalimido-percarboxylic acids in which the percarboxylic acidcontent comprises 1 to 8 carbon atoms as per-acids, and/or

c) per-acids with an alkyl or alkenyl group comprising 1 to 12 carbonatoms as per-acids of general formula III.

It is particularly preferred if one or more compounds selected fromperacetic acid, perpropionic acid, peroctanoic acid,phthalimidoperhexanoic acid, phthalimidoperoctanoic acid, perglycolicacid, perglycolic acid monomethyl ester, persuccinic acid, persuccinicacid monomethyl ester, perglutaric acid, perglutaric acid monomethylester, peradipic acid, peradipic acid monomethyl ester are contained asper-acids.

The preferred content of per-acids in the solutions which come intocontact with the medical apparatus according to the present invention is0.001 to 0.5% by weight, particularly preferably 0.01 to 0.2% by weight,based on the total disinfecting solution.

It is also preferred if an additional content of 0.0001 to 2.5% byweight, particularly preferably 0.001 to 0.5% by weight, of hydrogenperoxide comes into contact with the medical apparatus during the useaccording to the invention.

Moreover, it is preferred with the use according to the invention thatthe non-oxidized acid corresponding to the per-acid present and, in thecase of per-acid esters, the non-esterified form of the non-oxidizedacid also comes into contact with the medical apparatus.

The compositions to be used according to the invention contain fattyacids containing 8 to 12 carbon atoms, particularly preferably octanoicacid, as preferred fatty acids c1).

If the compositions to be used according to the invention containcomplexing components c4), these are preferably selected from componentshaving complexing properties for polyvalent metal ions.

Examples of components with complexing properties includenitrilotriacetic acid, ethylenediamine tetraacetic acid, methylglycinediacetic acid, gluconic acid, citric acid, dicarboxymethyl-L-glutamicacid, serine diacetic acid, imidosuccinic acid, the polycarboxylic andphosphonic acid group and the respective salts thereof. Examples ofpolycarboxylic acids include polyacrylic acids and copolymers of maleicacid anhydride and acrylic acid as well as the sodium salts of thesepolymeric acids. Conventional commercial products include Sokalan® CP 5and PA 30 made by BASF, Alcosperse® 175 and 177 made by Alco, LMW® 45 Nand SPO2 ND made by Norsohaas. Suitable natural polymers includeoxidised starch (for example, DE 42 28 786) and polyamino acids such aspolyglutamic acid or polyaspartic acid made by Cygnus, Bayer, Rohm &Haas, Rhône-Poulenc or SRCHEM, for example.

Examples of phosphonic acids include 1-hydroxyethane-1,1-diphosphonicacid, diethylenetriamine pentamethylene phosphonic acid orethylenediamine tetramethylene phosphonic acid and the alkali saltsthereof.

If the compositions to be used according to the invention containsurfactant components c3), these are preferably selected from the groupsconsisting of anionic, cationic, nonionic, amphoteric surfactants,alkylamine oxides, siloxane-based surfactants and surfactant phosphoricacid esters and salts thereof.

Preferred surfactant components include anionic surfactantsconventionally used in the field of detergents and cleaningcompositions, for example C₈-C₁₈ alkylsulfates, C₈-C₁₈alkylethersulfates, C₈-C₁₈ alkanesulfonates, C₈-C₁₈ olefin sulfonates,sulfonated C₈-C₁₈ fatty acids, C₈-C₁₈ alkylbenzenesulfonates,sulfosuccinic acid mono- and di-C₁-C₁₂ alkyl esters, C₈-C₁₈alkylpolyglycolethercarboxylates, C₈-C₁₈ N-acyltaurides, C₈-C₁₈N-sarcosinates, C₈-C₁₈ alkylisothionates and mixtures thereof.Trialkylamine oxide with an alkyl group containing 8 to 20 carbon atomsand two alkyl groups with a smaller number of carbon atoms in the alkylchain is preferably contained as amine oxide, wherein the two shorteralkyl groups may be the same or different and the amine oxide derivativeis particularly preferably tallow grease-bis-(2-hydroxyethyl)-amineoxide, oleyl-bis-(2-hydroxyethyl)-amine oxide,coconut-bis-(2-hydroxyethyl)-amine oxide, tetradecyldimethyl-amine oxideand/or alkyldimethyl-amine oxide containing 12 to 18 carbon atoms in thealkyl chain.

The nonionic surfactants in the compositions to be used according to theinvention are preferably alkylpolyglycosides which can normally beobtained industrially by condensation of fatty alcohols with glucose orpolyglucose and are commercially available in various forms. Examples ofalkylpolyglycosides which are particularly suitable for the useaccording to the invention include the products Glucopon® 600 made byHenkel and Triton® BG10 made by Rohm & Haas.

Further preferred nonionic surfactants include alkoxylated alkylalcohols containing 8 to 22 carbon atoms in the alkyl chain wherein, inparticular, at least one compound from the groups consisting of mixedethoxylates/propoxylates of branched or unbranched alkyl alcoholscontaining 8 to 22 carbon atoms in the alkyl chain and ethoxylatescomprising terminal groups, of branched or unbranched alkyl alcoholscontaining 8 to 22 carbon atoms in the alkyl chain is contained, andquite particularly preferably at least one compound from the groupsconsisting of ethoxylated and propoxylated alkyl alcohols containing 12to 22 carbon atoms in the alkyl part, the butyl ethers of ethoxylatedalkyl alcohols containing 12 to 22 carbon atoms in the alkyl part andmethyl ethers of ethoxylated alkyl alcohols containing 12 to 22 carbonatoms in the alkyl part, butyl ether and methyl ether of the ethoxylated2-octyl-1-dodecanol being contained in the specific case. Nonionicsurfactants which are particularly suitable for producing theformulations according to the invention include, for example, Plurafac®LF 403, Plurafac® 431 made by BASF and Dehypon® LT 104 and Dehypon® G2084 made by Henkel.

Phosphoric acid ester compounds, preferably including at least one saltof a phosphoric acid partial ester, are preferably used as surfactant inthe composition to be used according to the invention, at least onealkali salt of a phosphoric acid partial ester of alkoxylated alkylphenol particularly preferably being used.

Phosphoric acid esters are surfactant substances preferably derived fromlong-chain aliphatic or araliphatic alcohols. Salts of phosphoric acidpartial esters have proven particularly suitable, in particular thesalts of alkoxylated alkyl phenols in this case. Sodium and potassiumsalts are preferably used as alkali salts, the potassium salts beingparticularly preferred. Surfactant phosphoric acid partial esters of thetype which are preferably used according to the invention arecommercially available. An example of an active ingredient of this typewhich is particularly suitable according to the invention is the productTriton® H 66 (Rohm & Haas).

It is also preferable to select the hydrotrope c3) from the groupsconsisting of anionic surfactants which have already been dealt with inthe foregoing text but will be mentioned again owing to the specificfunction. Particularly preferred hydrotropes include sulfonates/sulfonicacids, in particular cumene, xylene, octyl, naphthyl andalkylbenzenesulfonates/sulfonic acids, the alkyl group containingbetween 6 and 16 carbon atoms in the last case.

It is also preferred if cleaning and disinfection take place insuccession in time in an automatic treatment process.

In a further preferred practical example, cleaning and disinfection takeplace simultaneously in time in an automatic treatment process.

The present invention also relates to cleaning compositions anddisinfectants for sensitive medical apparatus, in particular endoscopes,which are based on organic per-acids or salts of organic per-acidsselected from

a) compounds of general formula I

R—O₂C—(CH₂)_(x)—CO₃H  (I)

wherein R is hydrogen or an alkyl group containing 1 to 4 carbon atomsand x is a number from 1 to 4 and/or

b) compounds from the group consisting of phthalimido percarboxylicacids (II), wherein the percarboxylic acid content is 1 to 18 carbonatoms and/or

c) compounds of general formula I

R—O₂C—(CH₂)_(x)—CO₃H  (I)

wherein R is hydrogen or an alkyl group containing 1 to 4 carbon atomsand x is a number from 1 to 4 and/orcompounds from the group consisting of phthalimido percarboxylic acids(II), wherein the percarboxylic acid content comprises 1 to 18 carbonatoms, and/orcompounds of general formula III

R—CO₃H  (III)

wherein R represents an alkyl or alkenyl group containing 1 to 18 carbonatoms,in combination withc1) at least one fatty acid and/orc2) at least one hydrotrope and/orc3) at least one surfactant component and/orc4) at least one complexing component.

The foregoing explanations concerning the make-up of the compositions tobe used according to the invention are also preferred practical examplesof the disinfectant according to the invention for sensitive medicalapparatus.

The present invention also relates to a process for cleaning anddisinfecting sensitive medical apparatus, in particular endoscopes, inautomatically operating equipment, in which the apparatus are treatedwith a neutral or alkaline cleaning solution optionally containingenzymes in a first step and, optionally after intermediate rinsing withwater, the apparatus are brought into contact with an aqueous solutionof a cleaning composition and disinfectant according to the invention ina second step, and the apparatus are rinsed with water and thenoptionally dried in a third step.

Here also, the foregoing explanations concerning the make-up of thecompositions to be used according to the invention are also preferredpractical examples of the cleaning composition and disinfectant forsensitive medical apparatus.

EXAMPLES Example 1

Concentrates having the following composition have been produced bymechanical combination of the individual constituents:

Cleaning composition concentrate 10% by weight n-butyl ether of anaddition product of 9.5 mol ethylene oxide to 1 mol hardened tallowgrease alcohol (Dehypon LT 104, commercial product made by Henkel KgaA)3% by weight 1,2-propylene glycol 3% by weight sodium cumene sulfonate7% by weight triethanolamine 1% by weight citric acid to 100% by weightwater Disinfectant concentrate 5% by weight peracetic acid 25% by weighthydrogen peroxide 6% by weight acetic acid 1% by weight1-hydroxyethane-1,1-diphosphonic acid to 100% by weight water Buffersolution 5% by weight sodium hydroxide 1% by weight potassiumtripolyphosphate to 100% by weight water

The endoscopes were cleaned and disinfected in a sealable stainlesssteel vessel (about 60 cm×60 cm×65 cm) which was provided with a heaterand had been equipped with feed and discharge pipes for the cleaningcomposition and disinfectant solution and the water used in the rinsingcycles and for the hot air required for drying the apparatus.

Using a circulation pump, the liquids present in each case could bepumped into contact with the external surfaces of the apparatus by meansof a so-called spray arm and through the ducts of the endoscope by meansof special connections.

The experiments were carried out using conventional commercialendoscopes.

Water adjusted to a hardness of 5° d using a cation exchanger was usedto apply the cleaning composition and disinfectant solutions.

Ready-to-use cleaning composition and disinfectant solutions wereproduced by diluting appropriate amounts of cleaning concentrate,disinfectant concentrate and buffer solution.

The cleaning solution was adjusted to contain 0.5 g surfactant/l in thesolution for application.

The disinfectant solution was prepared so that it contained 0.5 gperacetic acid/l in the solution for application.

The endoscopes in a wire basket were immersed into the stainless steelcontainer when carrying out the cleaning and disinfecting process. Theducts of the endoscopes were attached to the circulation pump.Sufficient liquid was supplied to the stainless steel container in eachof the individual stages of the process for the external surface of theendoscopes to be sprayed intensively in a circulatory process and at thesame time for the liquid to be pumped continuously through the ducts ofthe endoscope.

The cleaning concentrate was dosed in a strength of 0.5% at 20° C., thecleaning solution circulated via the spray arm and through the ducts andheated to 35° C. Once the temperature was reached, the cleaning processwas continued for a further 2 minutes under constant conditions.

Two procedures designated hereinafter as test 1 and test 2 wereinvestigated for the subsequent disinfecting stage:

Test 1:

The cleaning solution was pumped away and disposed of and the endoscopethen filled with fresh water which had been mixed with 1% by weight ofthe disinfectant concentrate and with 1% by weight of the buffersolution, based on the total aqueous solution.

Test 2:

1% by weight of the disinfectant concentrate and 1% by weight of thebuffer solution, based on the total cleaning solution present, weredosed into the cleaning solution.

The solutions presented in test 1 and in test 2 were heated to 35° C.and circulated via the spray arm and through the ducts for a period of 5minutes and therefore brought into contact with the internal andexternal surfaces of the endoscope to be treated.

The solutions were pumped away and the endoscope rinsed twice internallyand externally with cold water.

To test the cleaning effect achieved with the process according to theinvention, the instrumentation duct of the endoscope was provided withartificial soil having the following composition:

9.85% by weight of heparinized sheep's blood0.15% by weight of protamine 1000

To determine the cleaning capacity, the endoscope was inspected forresidues. For this purpose, the ducts were rinsed with a 1% aqueoussodium dodecylsulfonate solution and the protein content determined bythe OPA method (cf. H. Frister and W. Michels, Hyg. Med. 1994, 19, 673to 688).

To check the disinfecting activity achieved with the process accordingto the invention, ‘Test 1 and Test 2’, the ducts of the endoscope werecontaminated with a blood/germ suspension containing the followinggerms:

a) about 10⁹ germs/ml of Staphylococcus aureus

b) about 10⁹ germs/ml Pseudomonas aeroginosa

c) about 10⁹ germs/ml Enterococcus faecium

0.35% by weight of the germ suspension were mixed with 9.5% by weight ofheparinized sheep's blood and 0.15% by weight of protamine 1000 in eachcase. This blood/germ suspension was then used to soil theinstrumentation duct (cf Hyg. Med. 1995, 20, 4047).

After carrying out the process according to the invention, ‘Test 1 andTest 2’, 0.51 of a solution containing 3% by weight Tween 80, 0.3% byweight lecithin, 0.1% histidine, 0.1% by weight trypton and 0.05% byweight sodium chloride was aspirated through the ducts of the endoscope.Samples each consisting of 1 ml of this solution were inoculated ontoagar plates which were subsequently fertilized for at least 48 hours at37° C. and 72 hours at 35° C. and then inspected for the existence ofgerm propagation. It has been found that, when carrying out the processaccording to the invention in both variant ‘Test 1’ and variant ‘Test2’, residual soiling could not be detected and the necessary freedomfrom germs had been achieved.

Further tests carried out under the above-described conditionsdemonstrated that the processes according to the invention according to‘Test 1 and Test 2’ could also be successfully used in the case ofcontamination by viruses, in particular entero viruses such as polioviruses, and also heat-resistant viruses such as papovaviruses.

Example 2

The antimicrobial range of activity of various combinations of per-acidswith selected additives was investigated at ambient temperature by theDVG (Deutsche Vererinärgesellschaft e.V.) quantitative suspension testin a second series of tests.

Staphylococcus aureus and Escherichia coli were used as test germs fordetermining the bactericidal activity. Saccharomyces cerevisiae andAspergillus niger were used as test germs for determining the fungicidalactivity. Table 2 shows the formulations tested. Table 3 and Table 4show the results of the quantitative suspension test.

It can been seen from the tabulated results that the range of activityof per-acids can be significantly improved by selected combinations.This is particularly important because safety during the automaticcleaning and disinfecting of sensitive medical apparatus can thus beimproved.

The additional components such as sulfonates/sulfonic acids, surfactantsand fatty acids are also known to have additional cleaning effects, soit is possible to remove, in a subsequent disinfecting stage, anyresidual soil which could not be removed in a first cleaning stage.

TABLE 2 Formulations for the microbiological experiment ComparisonComparison Raw material Form. 1 Form. 2 Form. 3 Form. 4 Form. 5 form. 1form. 2 Perglutaric acid 80 80 80 80 — — 100 monomethyl ester (10%)Peracetic acid — — — — 80 100 — (10%) Alkylbenzene-sulfonic 10 — — 10 10— — acid Dimethylcoconut-amine — 10 — — — — — oxide Sodium octylsulfonate — — 16  6  6 — — Octanoic acid — —  4  4  4 — — Water 10 10 —— — — —

TABLE 3 Results of the microbiological experiments against bacteriaStaphylococcus aureus Escherichia coli ATCC 6538 (K 3212) ATCC 10536 (K2124) Inoculum 7.05 × 10⁸ Inoculum 1.07 × 10⁹ KBE/ml KBE/ml [AWK] 1minute 5 minutes 1 minute 5 minutes Product % RF RF RF RF Comparison 0.11.3 >4.87 >5.2 >5.3 formulation 1 0.3 3.4 >4.87 >5.2 >5.3 Comparison 0.10.04 >4.87 3.69 >5.3 formulation 2 0.3 0.59 >4.87 >5.2 >5.3 Formulation1 0.1 3.42 >4.87 >5.2 >5.3 0.3 >4.9 >4.87 >5.2 >5.3 Formulation 2 0.1 00.09 1.17 >5.3 0.3 0.03 >4.87 >5.2 >5.3 Formulation 30.1 >4.9 >4.87 >5.2 >5.3 0.3 >4.9 >4.87 >5.2 >5.3 Formulation 4 0.13.04 >4.87 >5.2 >5.3 0.3 >4.9 >4.87 >5.2 >5.3 Formulation 5 0.13.2 >4.87 >5.2 >5.3 0.3 >4.9 >4.87 >5.2 >5.3 AWK = concentration forapplication; RF values = germ reduction in LOG stages

TABLE 4 Table of results for DVG fungicidal activity Saccharomycescerevisiae Aspergillus niger ATCC 9763 (K 5011) ATCC 16404 (K 7444)[AWK] Inoculum 1.36 × 10⁷ KBE/ml Inoculum 1.07 × 10⁹ KBE/ml Product % 5minutes RF 30 minutes RF 5 minutes RF 30 minutes RF Comparison 0.3 0.530.55 0 0 formulation 1 1.0 0.71 1.4 0 0 Comparison 0.3 0.21 0.24 0 0formulation 2 1.0 0.24 1.1 0 0 Formulation 1 0.3 2.88 >3.19 0 01.0 >3.18 >3.19 0 0.02 Formulation 2 0.3 0.55 >3.19 0 0.381.0 >3.18 >3.19 0.22 0.85 Formulation 3 0.3 >3.18 >3.19 0.31 0.541.0 >3.18 >3.19 1.56 4.02 Formulation 4 0.3 3.18 3.19 0.39 0.87 1.0 3.183.19 1.34 >4.02 Formulation 5 0.3 3.18 3.19 0.61 1.3 1.0 3.18 3.191.74 >4.02 AWK = concentration for application; RF values = germreduction in LOG stages

1-18. (canceled)
 19. A process for cleaning and disinfecting anendoscope, the process comprising: treating the endoscope with a neutralor alkaline cleaning composition; contacting the endoscope with anaqueous antimicrobial composition comprising peroctanoic acid, a fattyacid containing 8 to 12 carbon atoms, a hydrotrope, a component, and acomplexing component and having a pH from about 6.5 to about 8; andrinsing the endoscope with water; wherein the cleaning composition doesnot comprise an oxidizing agent and further, wherein the cleaning andthe antimicrobial treatment are carried out in succession with regard totime.
 20. The process of claim 19, wherein the contact time of theaqueous antimicrobial composition is between 1 and 15 minutes.
 21. Theprocess of claim 19, wherein the temperature of the aqueousantimicrobial composition is between 5 and 55° C.
 22. The process ofclaim 19, wherein the steps of contacting the endoscope with the aqueousantimicrobial composition comprises spraying, rinsing, or immersion. 23.The process of claim 19, wherein the antimicrobial composition comprises0.001 to 0.5% by weight of peroctanoic acid, based on the totalantimicrobial composition.
 24. The process of claim 19, wherein theantimicrobial composition further comprises 0.0001 to 2.5% by weight ofhydrogen peroxide, based on the total antimicrobial composition.
 25. Theprocess of claim 19, wherein the complexing component comprises at leastone component with complexing properties for polyvalent metal ions. 26.The process of claim 19, wherein the process takes place in an automatictreatment process.
 27. The process of claim 19, wherein the neutral oralkaline cleaning composition comprises an enzyme.
 28. The process ofclaim 19, further comprising a step of intermediate rinsing of water inbetween the step of treating the endoscope with the cleaning compositionand contacting the endoscope with the antimicrobial composition.
 29. Theprocess of claim 19, wherein the step of rinsing the endoscope withwater comprises drying.
 30. The process of claim 19, wherein thetemperature of the aqueous cleaning composition is between 15 and 45° C.31. The process of claim 19, wherein the fatty acid comprises octanoicacid.
 32. The process of claim 19, wherein the hydrotrope comprisesanionic surfactant.
 33. The process of claim 19, wherein the surfactantcomponent comprises anionic surfactant.